Technical Field
The present invention relates to a power-module substrate, a heat-sink-attached power-module substrate, and a heat-sink-attached power module used for a semiconductor device controlling large current and high voltage.
Priority is claimed on Japanese Patent Application No. 2014-91814, filed Apr. 25, 2014, the content of which is incorporated herein by reference.
Background Art
A structure conventionally known as a power-module substrate is the following: a metal plate to be a circuit layer is bonded on one side of surfaces of a ceramic substrate to be an insulating layer; and a metal plate to be a metal layer is bonded on the other side of the surfaces of the ceramic substrate. A heat-sink-attached power-module substrate is made by bonding a heat sink having an excellent thermal conductivity on the metal layer provided on one surface of the power-module substrate. A heat-sink-attached power module is made by mounting a semiconductor element such as a power device or the like on the circuit layer, with soldering material therebetween.
In the heat-sink-attached power-module substrate of this kind, as described in Patent Document 1, there is a case in which copper having an excellent electrical characteristics is used for the metal plate to be the circuit layer and aluminum is used for the metal plate to be the metal layer for a purpose of decreasing thermal stress between the ceramic substrate and the heat sink.